Iimoriyama Castle

Overview

Iimoriyama Castle (飯盛山城, Iimoriyama-jō) is a ruined mountain-top castle in Osaka Prefecture, Japan, sitting on a peak 315.9 metres high. Its ruins lie across two present-day cities, Shijōnawate-shi (四條畷市) and Daitō-shi (大東市), on the ridge that separates them. The castle is listed among the Continued Top 100 Japanese Castles (続日本100名城, Zoku Nihon Hyakujō), a 2017 selection of fortifications chosen by the Japanese Castle Foundation for their historical importance.

The site is significant on two counts. It was founded in 1333, at the very start of the Kenmu Restoration (建武の新政, Kenmu no shinsei), the brief period when Emperor Go-Daigo attempted to restore direct imperial rule. Two centuries later it became the original base of power for the Miyoshi clan (三好氏), one of the dominant warrior houses of the Sengoku period. The castle is also recorded as the place of death of Miyoshi Nagayoshi (三好長慶), the clan's most powerful leader.

History

Iimoriyama Castle was established in 1333, in the second year of the Shōkyō era (正慶, Shōkyō). That dating places its foundation in the same year that the Kamakura shogunate fell and the Kenmu Restoration began, a moment of open warfare across Japan as Emperor Go-Daigo's forces moved against the Hōjō regime. A mountain stronghold on the ridge between what are now Shijōnawate and Daitō belonged to that world of rapid fortification and contested authority.

The castle's greater fame comes from the Sengoku period (戦国時代, Sengoku jidai), the century and a half of near-constant regional warfare that ran roughly from the mid-fifteenth century to the end of the sixteenth. Iimoriyama was the original base of power for the Miyoshi clan, a warrior house that rose from the ranks of the shogunate's deputies in the Kinai region around Kyoto and eventually came to dominate the politics of the capital.

Miyoshi Nagayoshi, the clan's most successful leader, is recorded as having died at Iimoriyama Castle. Under Nagayoshi the Miyoshi held sway over Kyoto and the surrounding provinces in the middle decades of the sixteenth century, before their power was broken in the 1560s and 1570s by the advance of Oda Nobunaga. The castle on the mountain above the Osaka plain was the point from which that ascendancy began.

What Stands There Today

Nothing of the castle's buildings survives. Iimoriyama is a yamajiro (山城, yamajirō), a mountain castle, and like most such sites it is preserved as earthworks rather than architecture: the ridges and slopes of the 315.9-metre peak carry the flattened enclosures, terraced approaches and cut defences of the original fortification. The ruins are protected and interpreted as a heritage site, and their inclusion in the Continued Top 100 Japanese Castles reflects their standing among Japan's surviving mountain fortresses.

The site lies within the modern boundaries of Shijōnawate-shi and Daitō-shi, and the ridge itself is a recognised walking route in the hills east of Osaka.

The Name in Japanese

The castle's name is written 飯盛山城 and read いいもりやまじょう (Iimoriyama-jō). It breaks into four characters, each doing a distinct job.

• 飯 — read ii here. The character means "cooked rice" or "meal". On its own the standard reading is meshi; the ii used in this name is an older Japanese reading preserved inside place names.
• 盛 — read mori. The character means "to heap up", "to serve (food)", or "to flourish". Combined with 飯 it gives ii-mori, "rice-serving" or "heaped rice" — the image of a bowl of rice piled high.
• 山 — read yama. The character means "mountain". It is the most common element in Japanese castle names, and its presence here marks Iimoriyama as a mountain castle rather than one built on the flat.
• 城 — read jō. The character means "castle". In compound castle names it is normally read jō, as in this word; the native Japanese reading shiro appears when the character stands alone.

So the full name means "Rice-Heaped Mountain Castle" — a castle on the mountain whose profile, presumably, resembled a piled bowl of rice. The pattern 山 + 城 (yama + jō) is the standard formula for a mountain-top fortress, and it tells a reader immediately what kind of site Iimoriyama was.

Visiting and Context

Iimoriyama Castle is an outdoor site, reached on foot along the ridge trails above Shijōnawate and Daitō, east of central Osaka. Visitors should expect earthworks, viewpoints and forest rather than reconstructed buildings; the reward is the shape of the mountain defences themselves and the view across the plain that the Miyoshi clan once controlled.

The castle sits in a dense historical landscape. Shijōnawate is the site of the 1348 Battle of Shijōnawate (四條畷の戦い, Shijōnawate no tatakai), fought between the Northern and Southern courts during the Nanboku-chō period, and the wider area east of Osaka holds a concentration of Sengoku-era mountain forts. Iimoriyama's place in that network — a Kenmu-era foundation that became the launch point for the Miyoshi ascendancy and the death place of Miyoshi Nagayoshi — makes it one of the more historically layered ruins in the Kansai region.